A phase transition refers to a transformation of a system from one phase to another. Examples of phase transitions include conductance transitions, as well as transitions between solid, liquid and gaseous states of matter.
Conductance transitions involve transitions between different conductance states. For example, metal-insulator transitions refer to transitions between a metallic (or conducting) state and an insulating (or non-conducting) state. Conductance transitions may be induced by external stimuli such as temperature, electric field, magnetic field, photons and rapid fluctuations in the local environment.
Recently, much research effort has been devoted to materials that are capable of undergoing very fast phase transitions (for example, metal-insulator transitions) under certain conditions. There are many potential applications for such materials.